In side-channel pumps, it is necessary to maintain a tight play between the vane and the surrounding casing parts. If the gap becomes too large, the leakage flows within the pump increase and pumping capacity and effectiveness decline. Since the vanes must also be prevented, as far as possible, from running up against the casing parts, this means that those casing parts of the pump which enclose the vane, and the vane itself, must be accurately centred one to another and must be set perpendicular to the shaft. Finally, care should be taken in side-channel pumps to ensure that both the vane and the casing exhibit high strength characteristics, since side-channel pumps, in contrast to normal-intake pumps, can achieve many times higher pressures given equal pump dimensions and rotation speeds. This is particularly true of sectional pumps having a plurality of stages, in which very high pressures are obtained with just a relatively low number of stages. All these aspects have hitherto resulted in the casing parts which enclose the vane generally being constructed as metallic castings in which the interacting faces are worked with tight production tolerances. Although a pump of similar type, namely a peripheral pump, has been disclosed (GB-A 968 511), in which all pump casing parts are formed from sheet metal, this is only conceivable where the requirements in terms of trueness of running and efficiency are very low.